| 1. |
- Guergueltcheva, V., et al.
(författare)
-
Congenital myasthenic syndrome with tubular aggregates caused by GFPT1 mutations
- 2012
-
Ingår i: Journal of Neurology. - : Springer Science and Business Media LLC. - 0340-5354 .- 1432-1459. ; 259:5, s. 838-850
-
Tidskriftsartikel (refereegranskat)abstract
- Congenital myasthenic syndrome (CMS) is a clinically and genetically heterogeneous group of inherited disorders of the neuromuscular junction. A difficult to diagnose subgroup of CMS is characterised by proximal muscle weakness and fatigue while ocular and facial involvement is only minimal. DOK7 mutations have been identified as causing the disorder in about half of the cases. More recently, using classical positional cloning, we have identified mutations in a previously unrecognised CMS gene, GFPT1, in a series of DOK7-negative cases. However, detailed description of clinical features of GFPT1 patients has not been reported yet. Here we describe the clinical picture of 24 limb-girdle CMS (LG-CMS) patients and pathological findings of 18 of them, all carrying GFPT1 mutations. Additional patients with CMS, but without tubular aggregates, and patients with non-fatigable weakness with tubular aggregates were also screened. In most patients with GFPT1 mutations, onset of the disease occurs in the first decade of life with characteristic limb-girdle weakness and fatigue. A common feature was beneficial and sustained response to acetylcholinesterase inhibitor treatment. Most of the patients who had a muscle biopsy showed tubular aggregates in myofibers. Analysis of endplate morphology in one of the patients revealed unspecific abnormalities. Our study delineates the phenotype of CMS associated with GFPT1 mutations and expands the understanding of neuromuscular junction disorders. As tubular aggregates in context of a neuromuscular transmission defect appear to be highly indicative, we suggest calling this condition congenital myasthenic syndrome with tubular aggregates (CMS-TA).
|
|
| 2. |
- Senderek, J, et al.
(författare)
-
Hexosamine Biosynthetic Pathway Mutations Cause Neuromuscular Transmission Defect
- 2011
-
Ingår i: American journal of human genetics. - 0002-9297. ; 88:2, s. 162-172
-
Tidskriftsartikel (refereegranskat)abstract
- Neuromuscular junctions (NMJs) are synapses that transmit impulses from motor neurons to skeletal muscle fibers leading to muscle contraction. Study of hereditary disorders of neuromusculartransmission, termed congenital myasthenic syndromes (CMS), has helped elucidate fundamental processes influencing development and function of the nerve-muscle synapse. Using genetic linkage, we find 18 different biallelic mutations in the gene encoding glutamine-fructose-6-phosphate transaminase 1 (GFPT1) in 13 unrelated families with an autosomal recessive CMS. Consistent with these data, downregulation of the GFPT1 ortholog gfpt1 in zebrafish embryos altered muscle fiber morphology and impaired neuromuscular junction development. GFPT1 is the key enzyme of the hexosaminepathway yielding the amino sugar UDP-N-acetylglucosamine, an essential substrate for protein glycosylation. Our findings provide further impetus to study the glycobiology of NMJ and synapses in general.
|
|
| 3. |
- Ebin, B., et al.
(författare)
-
Electrochemical properties of nanocrystalline LiFe xMn 2-xO 4 (x = 0.2-1.0) cathode particles prepared by ultrasonic spray pyrolysis method
- 2012
-
Ingår i: Electrochimica Acta. - : Elsevier BV. - 0013-4686 .- 1873-3859. ; 76, s. 368-374
-
Tidskriftsartikel (refereegranskat)abstract
- The nanocrystalline LiFe xMn 2-xO 4 (x = 0.2-1.0) particles were prepared by ultrasonic spray pyrolysis method using nitrate salts of ingredients at 800°C in air atmosphere. Particle properties were characterized by X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy. Besides, cyclic voltammetry and galvanostatic tests were performed to investigate the effects of the iron substituent amount on electrochemical behavior. Particle characterization studies show that nanocrystalline particles have spinel structure and they are in submicron size range with spherical morphology. The lowest iron doped sample (LiFe 0.2Mn 1.8O 4) exhibits 117 mAh g -1 cumulative discharge capacity at 0.5 C and 88% capacity retention for 4 V plateau after 50 cycles. At higher iron concentrations, substituent tends to occupy the 8a tetrahedral sites, which prevent the lithium transport in the lattice during charge-discharge process. Increasing of the iron amount in the spinel structure causes the deterioration of the electrochemical performance.
|
|
| 4. |
|
|
| 5. |
- Lindahl, Niklas, 1981, et al.
(författare)
-
Fuel Cell Measurements with Cathode Catalysts of Sputtered Pt3Y Thin Films
- 2018
-
Ingår i: ChemSusChem. - : Wiley. - 1864-5631 .- 1864-564X. ; 11:9, s. 1438-1445
-
Tidskriftsartikel (refereegranskat)abstract
- Fuel cells are foreseen to have an important role in sustainable energy systems, provided that catalysts with higher activity and stability are developed. In this study, highly active sputtered thin films of platinum alloyed with yttrium (Pt 3 Y) are deposited on commercial gas diffusion layers and their performance in a proton exchange membrane fuel cell is measured. After acid pretreatment, the alloy is found to have up to 2.5 times higher specific activity than pure platinum. The performance of Pt 3 Y is much higher than that of pure Pt, even if all of the alloying element was leached out from parts of the thin metal film on the porous support. This indicates that an even higher performance is expected if the structure of the Pt 3 Y catalyst or the support could be further improved. The results show that platinum alloyed with rare earth metals can be used as highly active cathode catalyst materials, and significantly reduce the amount of platinum needed, in real fuel cells.
|
|
| 6. |
- Medard, C., et al.
(författare)
-
Oxygen reduction by Fe-based catalysts in PEM fuel cell conditions : Activity and selectivity of the catalysts obtained with two Fe precursors and various carbon supports
- 2006
-
Ingår i: Electrochimica Acta. - : Elsevier BV. - 0013-4686 .- 1873-3859. ; 51:16, s. 3202-3213
-
Tidskriftsartikel (refereegranskat)abstract
- Fe-based catalysts for the oxygen reduction reaction (ORR) in polymer electrolyte membrane (PEM) fuel cell conditions have been prepared by adsorbing two Fe precursors on various commercial and developmental carbon supports. The resulting materials have been pyrolyzed at 900C in an atmosphere rich in NH3. The Fe precursors were: iron acetate (FeAc) and iron tetramethoxy phenylporphyrin chloride (ClFeTMPP). The nominal Fe content was 2000 ppm (0.2 wt.%). The carbon supports were HS300, Printex XE-2, Norit SX-Ultra, Ketjenblack, EC-600JD, Acetylene Black, Vulcan XC-72R, Black Pearls 2000, and two developmental carbon black powders, RC1 and RC2 from Sid Richardson Carbon Corporation. The catalyst activity for ORR has been analyzed in fuel cell tests at 80 C as well as by cyclic voltammetry in O-2 saturated H2SO4 at pH 1 and 25 C, while their selectivity was determined by rotating ring-disk electrode in the same electrolyte. A large effect of the carbon support was found on the activity and on the selectivity of the catalysts made with both Fe precursors. The most important parameter in both cases is the nitrogen content of the catalyst surface. High nitrogen content improves both activity towards ORR and selectivity towards the reduction of oxygen to water (4e(-) reaction). A possible interpretation of the activity and selectivity results is to explain them in terms of two Fe-based catalytic sites: FeN2/C and FeN4/C. Increasing the relative amount of FeN2/C improves both activity and selectivity of the catalysts towards the 4e(-) reaction, while most of the peroxide formation may be attributed to FeN4/C. When FeAc is used as Fe precursor, iron oxide and/or hydroxide are also formed. The latter materials have low catalytic activity for ORR and reduce O-2 mainly to H2O2.
|
|
| 7. |
- Nordlund, Joakim, et al.
(författare)
-
The design and usage of a visual direct methanol fuel cell
- 2004
-
Ingår i: Journal of Applied Electrochemistry. - 0021-891X .- 1572-8838. ; 34:8, s. 763-770
-
Tidskriftsartikel (refereegranskat)abstract
- In order to better understand the influence of gas evolution on the performance of the direct methanol fuel cell ( DMFC) anode, a visual DMFC, comprising of a transparent anode and a cathode endplate with an integrated heat exchanger, and a picture analysis methodology were developed. The result was an inexpensive, but very powerful, tool for analyzing the role of two-phase flow. An important finding is that gas bubbles do not appear uniformly throughout the fluid flow matrix, but rather only at a few active sites. Another important finding is that the gas saturation ( volume fraction of gas/volume fraction of liquid) increases along the streamwise direction.
|
|
